This invention utilizes pressure measurements in an HVAC system to determine when an air filter has been clogged to the point that it should be replaced.
Filters are utilized to provide clean air to an HVAC system for circulation within an environment to be heated or cooled. As is known, the filter is typically placed upstream of a fan, and air is sucked through the filter, with impurities removed from the air.
Over time, the filter becomes clogged, and eventually should be replaced. A clogged filter presents challenges to the further operation of the fan, and increases the load on the fan. Further, at some point, the filter may become so full that it ceases to allow air flow, which is also undesirable.
In the prior art, there have been recommendations for periodic replacement of the filter. As an example, one known thermostat is provided with a signal recommending filter replacement after a period of time since the prior filter replacement. However, such systems are based upon assumptions of filter condition, and not on actual filter condition. Such assumptions can result in the filter being replaced too frequently, or not frequently enough.
One known system utilizes a control that monitors the fan speed, and predicts that the filter may be dirty, if fan speed indicates the filter is dirty. While this method is more beneficial than the prior art “assumption” method, it would still be desirable to provide alternative ways of determining filter condition.